Technical Field
The disclosure relates to a sensing technique, and particularly relates to an image sensor and an image sensing method.
Description of Related Art
Along with development of image sensing technique, when an image sensor senses an image, how to achieve both characteristics of “high dynamic range” and “high sensitivity” of a sensed image is always a problem in the image sensing technique that cannot be resolved. Particularly, in view of image capturing of industrial inspection of DUT (device under test) with high reflective surface or a backlighted shot, etc., these image sensing situations may encounter the problem with great contrast, which means a great difference between a highest illuminance and a lowest illuminance in the scene. Therefore, in order to guarantee unstauration of an output voltage of each pixel of the image sensor, a light sensitivity of each pixel has to be decreased, such that the output voltage of the pixel with the highest illuminance is not saturated. However, the method of getting the great contrast may cause loss of details of a darker portion in the scene, i.e. a light intensity resolution of the darker portion is deteriorated.
In this regard, a conventional solution is to capture more reference pictures with different parameters in the image capturing and process the two or more reference pictures to obtain a specific picture of balancing both characteristics of “high dynamic range” and “high sensitivity”. However, the conventional image sensing method is not adapted to a fast-motion image situation. Therefore, how to design an image sensor capable of obtaining the specific picture with high dynamic range and high sensitivity, and adapted to the fast-motion image situation is an import issue for related technicians.